Touch panel

1. A touch panel comprising: a top transparent substrate coated with a top conductive film on its lower surface; a bottom transparent substrate coated with a bottom conductive film on its upper surface; an insulating spacer located between the two conductive films of the top and bottom transparent substrates to separate the two conductive films, wherein when the top transparent substrate is touched by an external force, electric contact occurs between the two conductive films; and a plurality of signal lines, wherein each signal line is disposed on an edge of the top or bottom conductive film and is separated from another conductive film or another signal line by an adhesive, wherein a first trench, recessed into the top transparent substrate, is provided on an edge of the lower surface of the top transparent substrate and a signal line is disposed on the top conductive film in the first trench, or a second trench, recessed into the bottom transparent substrate, is provided on an edge of the upper surface of the bottom transparent substrate and a signal line is disposed on the bottom conductive film in the second trench.

2. The touch panel as claimed in claim 1 , wherein the top and bottom transparent substrates are glass or plastic.

3. The touch panel as claimed in claim 2 , wherein the top and bottom transparent substrates are polyester plastic.

4. The touch panel as claimed in claim 2 , wherein the top and bottom transparent substrates are flexible plastic.

5. The touch panel as claimed in claim 1 , wherein the signal lines are metal lines.

6. The touch panel as claimed in claim 1 , wherein a first trench is provided on an edge of the lower surface of the top transparent substrate and a signal line is disposed on the top conductive film in the first trench, and a second trench is provided on an edge of the upper surface of the bottom transparent substrate and a signal line is disposed on the bottom conductive film in the second trench.

7. The touch panel as claimed in claim 1 , wherein the plurality of signal lines includes: two top signal sensing lines disposed on two opposite edges of the top conductive film; two bottom signal sensing lines disposed on two opposite edges of the bottom conductive film; wherein the top signal sensing line and the bottom signal sensing line are arranged at a right angle.

8. The touch panel as claimed in claim 7 , wherein a plurality of signal lines further include four signal transmission lines connected to the signal sensing lines respectively.

9. The touch panel as claimed in claim 8 , wherein the lower surface of the top transparent substrate is provided with a trench on two edges arranged at a right angle, and a signal sensing line and a signal transmission line are disposed on the top conductive film in the trench.

10. The touch panel as claimed in claim 8 , wherein the top surface of the bottom transparent substrate is provided with a trench on two edges arranged at a right angle, and a signal sensing line and a signal transmission line are disposed on the bottom conductive film in the trench.

11. The touch panel as claimed in claim 1 , wherein the conductive film is indium tin oxide (ITO).

12. The touch panel as claimed in claim 1 , wherein the adhesive is a double-sided adhesive.

13. A touch panel comprising: a first transparent substrate having a first trench recessed into a first surface thereof; a first conductive film coated onto the first surface and the first trench; a second transparent substrate having a second surface facing the first surface; a second conductive film coated on the second surface facing the first conductive film; an insulating spacer located between and separating the two conductive films, wherein the first transparent substrate, the second transparent substrate, and the insulating spacer are arranged such that deformation of one of the first or second transparent substrates towards the other causes electrical contact to occur between the first and second conductive films; and a first signal line disposed in the first trench.

14. The touch panel as claimed in claim 13 , wherein the first trench is located at an edge of the first conductive film.

15. The touch panel as claimed in claim 13 , further comprising an adhesive disposed between the first transparent substrate and the second transparent substrate separating the first signal line from the second conductive film.

16. The touch panel as claimed in claim 13 , further comprising: a second trench formed recessed into the second surface of the second transparent substrate, wherein the second conductive film coats the second trench; a second signal line disposed in the second trench.

17. The touch panel as claimed in claim 16 , wherein the second trench is located at an edge of the second conductive film.

18. The touch panel as claimed in claim 16 , further comprising an adhesive disposed between the first transparent substrate and the second transparent substrate separating the first signal line from the second signal line.